Found a bug with sub-class detection. In short, it is not working.

It requires some thought.

src/mongopersist/README.txt

@@ -371,12 +371,18 @@ In order to accomplish collection sharing, you simply create another class
 that has the same ``_p_mongo_collection`` string as another (sub-classing will
 ensure that).
 
-So let's give Stephan an extended address now.
+So let's give Stephan two extended addresses now.
 
   >>> dm.root['stephan'].address2 = ExtendedAddress(
   ...     'Tettau', '01945', 'Germany')
   >>> dm.root['stephan'].address2
   <ExtendedAddress Tettau (01945) in Germany>
+
+  >>> dm.root['stephan'].address3 = ExtendedAddress(
+  ...     'Arnsdorf', '01945', 'Germany')
+  >>> dm.root['stephan'].address3
+  <ExtendedAddress Arnsdorf (01945) in Germany>
+
   >>> transaction.commit()
 
 When loading the addresses, they should be of the right type:
@@ -387,6 +393,13 @@ When loading the addresses, they should be of the right type:
   <ExtendedAddress Tettau (01945) in Germany>
 
 
+XXX: BUG with detecting derived classes properly. So for now just specify the
+collection explicitely.
+
+#  >>> dm.root['stephan'].address3
+#  <ExtendedAddress Arnsdorf (01945) in Germany>
+
+
 Tricky Cases
 ------------
 

src/mongopersist/datamanager.py

@@ -238,6 +238,8 @@ def _flush_objects(self):
         # object just once.
         written = []
         for obj in self._registered_objects:
+            __traceback_info__ = obj
+            orig = obj
             if getattr(obj, '_p_mongo_sub_object', False):
                 # Make sure we write the object representing a document in a
                 # collection and not a sub-object.

src/mongopersist/serialize.py

@@ -95,7 +95,9 @@ def __init__(self, jar):
 
     def get_collection_name(self, obj):
         __traceback_info__ = obj
-        db_name = getattr(obj, '_p_mongo_database', self._jar.default_database)
+        db_name = getattr(
+            obj, '_p_mongo_database',
+            self._jar.default_database if self._jar else None)
         try:
             coll_name = obj._p_mongo_collection
         except AttributeError:
@@ -267,6 +269,7 @@ def store(self, obj, ref_only=False):
             # XXX: Handle newargs; see ZODB.serialize.ObjectWriter.serialize
             # Go through each attribute and search for persistent references.
             doc = self.get_state(obj.__getstate__())
+
         if getattr(obj, '_p_mongo_store_type', False):
             doc['_py_persistent_type'] = get_dotted_name(obj.__class__)